[Docstring-checkins] CVS: dps/dps nodes.py,1.27,1.28

[David G. <go...@us...>]

Update of /cvsroot/docstring/dps/dps
In directory usw-pr-cvs1:/tmp/cvs-serv18778/dps/dps

Modified Files:
	nodes.py 
Log Message:
  - Added ``Node.walkabout()`` and "depart" methods to visitors.

Index: nodes.py
===================================================================
RCS file: /cvsroot/docstring/dps/dps/nodes.py,v
retrieving revision 1.27
retrieving revision 1.28
diff -C2 -d -r1.27 -r1.28
*** nodes.py	12 Feb 2002 02:21:18 -0000	1.27
--- nodes.py	13 Feb 2002 02:26:54 -0000	1.28
***************
*** 43,49 ****
      def walk(self, visitor):
          """
!         Traverse a tree of `Node` objects, calling ``visit_*`` methods of
!         `visitor`. If there is no ``visit_particular_node`` method for a node
!         of type ``particular_node``, the ``unknown_visit`` method is called.
  
          Doesn't handle arbitrary modification in-place during the traversal.
--- 43,50 ----
      def walk(self, visitor):
          """
!         Traverse a tree of `Node` objects, calling ``visit_...`` methods of
!         `visitor` when entering each node. If there is no
!         ``visit_particular_node`` method for a node of type
!         ``particular_node``, the ``unknown_visit`` method is called.
  
          Doesn't handle arbitrary modification in-place during the traversal.
***************
*** 60,63 ****
--- 61,84 ----
              children[i].walk(visitor)
  
+     def walkabout(self, visitor):
+         """
+         Perform a tree traversal similarly to `Node.walk()`, except also call
+         ``depart_...`` methods before exiting each node. If there is no
+         ``depart_particular_node`` method for a node of type
+         ``particular_node``, the ``unknown_departure`` method is called.
+ 
+         Parameter `visitor`: A `NodeVisitor` object, containing ``visit_...``
+         and ``depart_...`` methods for each `Node` subclass encountered.
+         """
+         method = getattr(visitor, 'visit_' + self.__class__.__name__,
+                          visitor.unknown_visit)
+         method(self)
+         children = self.getchildren()
+         for i in range(len(children)):
+             children[i].walkabout(visitor)
+         method = getattr(visitor, 'depart_' + self.__class__.__name__,
+                          visitor.unknown_departure)
+         method(self)
+ 
  
  class Text(Node, MutableString):
***************
*** 748,752 ****
      override individual methods for specific and useful behaviour. The
      "``visit_`` + node class name" method is called by `Node.walk()` upon
!     entering a node.
  
      .. [GoF95] Gamma, Helm, Johnson, Vlissides. *Design Patterns: Elements of
--- 769,774 ----
      override individual methods for specific and useful behaviour. The
      "``visit_`` + node class name" method is called by `Node.walk()` upon
!     entering a node. `Node.walkabout()` also calls the "``depart_`` + node
!     class name" method before exiting a node.
  
      .. [GoF95] Gamma, Helm, Johnson, Vlissides. *Design Patterns: Elements of
***************
*** 759,768 ****
  
      def unknown_visit(self, node):
!         """Called for unknown `Node` types. Does nothing unless overridden."""
!         pass
  
      # Save typing with dynamic definitions.
      for name in node_class_names:
          exec """def visit_%s(self, node): pass\n""" % name
      del name
  
--- 781,805 ----
  
      def unknown_visit(self, node):
!         """
!         Called when entering unknown `Node` types.
! 
!         Raise an exception unless overridden.
!         """
!         raise NotImplementedError('visiting unknown node type: %s'
!                                   % node.__class__.__name__)
! 
!     def unknown_departure(self, node):
!         """
!         Called before exiting unknown `Node` types.
! 
!         Raise exception unless overridden.
!         """
!         raise NotImplementedError('departing unknown node type: %s'
!                                   % node.__class__.__name__)
  
      # Save typing with dynamic definitions.
      for name in node_class_names:
          exec """def visit_%s(self, node): pass\n""" % name
+         exec """def depart_%s(self, node): pass\n""" % name
      del name
  
***************
*** 773,784 ****
      Generic "Visitor" abstract superclass, for simple traversals.
  
!     Unless overridden, each ``visit_*`` method calls `default_visit()`.
!     ``default_visit()`` must be overridden in subclasses.
  
!     Define fully generic visitors by overriding ``default_visit()`` only.
!     Define semi-generic visitors by overriding individual ``visit_*()``
!     methods also.
  
!     `NodeVisitor.unknown_visit()` should be overridden for default behavior.
      """
  
--- 810,824 ----
      Generic "Visitor" abstract superclass, for simple traversals.
  
!     Unless overridden, each ``visit_...`` method calls `default_visit()`, and
!     each ``depart_...`` method (when using `Node.walkabout()`) calls
!     `default_departure()`. `default_visit()` (`default_departure()`) must be
!     overridden in subclasses.
  
!     Define fully generic visitors by overriding `default_visit()`
!     (`default_departure()`) only. Define semi-generic visitors by overriding
!     individual ``visit_...()`` (``depart_...()``) methods also.
  
!     `NodeVisitor.unknown_visit()` (`NodeVisitor.unknown_departure()`) should
!     be overridden for default behavior.
      """
  
***************
*** 787,793 ****
--- 827,839 ----
          raise NotImplementedError
  
+     def default_departure(self, node):
+         """Override for generic, uniform traversals."""
+         raise NotImplementedError
+ 
      # Save typing with dynamic definitions.
      for name in node_class_names:
          exec """def visit_%s(self, node):
                      self.default_visit(node)\n""" % name
+         exec """def depart_%s(self, node):
+                     self.default_departure(node)\n""" % name
      del name